Maomao is the only standout example I can think of. She is absolutely surrounded by sex, and occasionally romance, but only ever engages with it at an intellectual level. I'd appreciate it if someone familiar with the ace/aro spectrum could give an analysis of her (non)sexuality.
Addressing some of the other suggestions:
Myne from Bookworm is a child for most of the series (which is a lot.) If your head canon is that she is ace and mostly aro, you can read it without cognitive dissonance. Potential marriage partners for her are a plot point on several occasions, and romantic attraction or how hot the potential partner is are not factors in her reaction to the possible pairings. If you haven't read Bookworm, you should, not because of ace representation, but because it is Bookworm.
Wild Last Boss just never thinks about romance (at least that I remember) so although technically every character could be considered ace/aro, it doesn't give me ace/aro vibes.
